Treatment of motor fuel



Patented June 14, 1938 Charles G. Dryer, Chicago, 111., ass'ignor toUniversal Oil Products ComparmOhicago, 111., a corporation oi'DelawareSerial No. 38,793

No Drawing. Application August 31,1935,

16 Claims.

. This invention relates to the treatment of.

hydrocarbon motor fuels produced as the main product in petroleumcracking operations, though the process may also be applied to analogousfrac- 5 tions of similar boiling range produced in' the distillation ofother types of hvdrocarbonaceous 'materials or to various motor fuelblends comprising stocks from different sources. p More specifically,the invention is concerned I with a method of treatment which results inthe,

stabilization of various types of gasolines which have a tendency todeteriorate on storage with loss in such valuable properties as lightcolor,

low gum content and antiknock value, the de-. teriora'tion beingdueprincipally to the action of oxygen and being accelerated by. thephotochemicalefiects of sunlight.

.- As a rule, little trouble is experienced in loss I of the abovementioned properties during the. storage of straight run gasolines,since there are substantially no oleflns in the lower boiling fractionsof crude oils, though tests indicate that higher molecular weightoleflns may be present in the higher boiling fractions. The crackingprocess, however, which is employed to produce additional yields ofgasoline from gas oils and petroleum residua invariably producesdefinite yields of unsaturated aliphatic hydrocarbons which have varyingdegrees of stability depending upon the type or \msaturation whichcharacter- 'izes them. The mono olefins are essentially stable even indirect contact withair and sunlight.

Conjugated dioleflns, however, such as butadiene and its derivatives,which are present in cracked gasolines produced under intensivecrackingconditions, have been shown to be the compounds which firstaddoxygen to produce derivatives of a peroxidic character which in turn actautocatalytically to cause further oxygen addition with 40 thedevelopment of gummy materials, compounds causing color and haze andultimately definite amoimts ot acids, aldebydes, ketones and other o yen-containing compounds.

The art of using inhibitors to retard the re- 7 -actions ofdeterioration occurring-in unstable gasoline has been developed to aconsiderable extent, and has largely overcome the disadvan-.-

tages inherent in the chemical treatments aimed at stabilization, whichentailed both-loss of maso terlal and loss in antilrnock rating. Use hasbeen madeoi a, wide variety or materials including both-pureicompoundsand mixtures, and apparently the materials represent a large number ofdiilsrent'chemicsl classes. They all. however,

have omnmon characteristic,- which is that (or sil -9) tuted paraaminophenols and Monoalkylp-aluinophenols Diaikylphenylone diamines"they either preferentially absorb oxygen and prevent the initialformation of oleilnic peroxides or that they decompose the peroxidesinitially formed so that the reactions of deterioration are halted for aperiod of time depending upon the 5 amount and potency of the inhibitor.The pres-.

ent invention is a contribution to the inhibitor art and consists in theuse of a particularly eilicient class of blended materials as inhibitorsin unstable'hydrocarbon mixtures, particularly motor fuels.

' In one specific embodiment, the present inven-. tion comprisesthe'treatment of unstable cracked gasolines to preserve their valuableproperties in respect to gum content, color and an'tiknock 15 value withalcoholic "solutions of alkyl-substi-f alkyl-substitutedparaphenylenediamines.

- 'An extensive series on investigations has indicated that solutions01' the above character are 20 particularly efficient in inhibiting thedeteriora-e tion of cracked gasolines andfthat they -.are furthermorereadily dispersed and dissolved when added in the relatively smallquantities which have been found to be necessary for the proper 25protection of gasoline. The invention is therefore a definitecontribution to the inhibitor art irom two very practical standpoints,(1) that of furnishing inhibitors of high potency, and (2) that offurnishing a liquid material which is readily handled and quicklydissolved.

The general formulas of the two classes-of compounds which are dissolvedin alcohol in varying proportions to form the present type of inhibitorsare given below, in which R. represents 'alkyl-substituting groups andthe other letters have their usual chemical significance.

R-N-H R-NI i B may represent methyl, ethyl,'propyl, butyl, -amyl, hexyland-other higher molecular weight aliphatic residues, andin'cludes" theisomeric forms; For example, mixtures 01' monomethyl 5 p-aminophenol anddimethyl p-phenylenediamine may be dissolved-in a suitable alcohol ormixtures may be madeoi" compounds in which the substituting. groups. arediil erent .orabsent in one oi the compounds. .An example oi mixed'isoamyl p-am inophenol and either p-phenylenediamine di-isoamylp-phenylenediamine. Obviously, by' varying the character of the alkyl-'substituting groups in the main classes of compounds and also theproportions thereof, a large number of alternative combinations arepossible, which, however, will not have exactly the same inhibitingefliciency in a given unstable gasoline or the 'same comparativeefllciency in different gasoline, so that various combinations are notexact equivalents. Furthermore, different compounds which are proposedas inhibitors will have different solubilities in different alcohols andblends thereof so that the amount of solvent necessary for making asufficiently fluid inhibitor and assisting its dispersion throughout alarge body of gasoline will also vary. Also either or both of theclasses of compounds referred to may be treated in accordance with theinvention.

It is particularly to be noted-that all of the members of the twoclasses of substituted compounds whose single or joint use is proposedas inhibitors are solids at ordinary temperatures and a as such aredifiicult to handle and difficult to dissolve in gasolines requiringinhibitors. The discovery that these compounds which have highinhibiting potency when properly dispersed through a body of gasolinecould be easily handied and quickly dissolved when utilized in alco-.holic solution is one of the notable contributions to the inhibitor artwhich characterizes the present invention. The various alcohols whichmay be used, which comprise usually the lower inc-- lecular weightaliphatic alcohols, have difierent cates also'whether a gasoline towhich the solution was added in the concentration of 0.004% remainedperfectly clear or precipitated out a small quantity of insolublematerial. Incidentally thetable also shows the corresponding inductionperiods of the gasoline to which the inhibitors were added, this figureindicating the time to measurable oxygen absorption in the standard bombtest:

Solvent action of alcohols I l t t C dlti i' ti so van on on 0 onsolvent 1 part of gasoline period,

solid minutes Methyl alcohol, absolute. 1 Cloudy 325 Do 2 Slightlycloudy 325 Do 5 Cloudy 330 Ethyl alcohol, absolute. 1 Clean... 345 Do 2do. 350 5 ldo 355 1 .do. 335 2 do.- 350 5 do 360 1 d0 340 2 do 330 5---do 345 The above table indicates that generally in the case of thesolid combination employed, the solvent action of the aliphatic alcoholsincreased with increasing molecular weight, though the induction perioddid not vary to any great extent.

When the gasoline was cloudy or hazy after the addition of the inhibitorblend, .it eventually separated some slight precipitate.

, The following table is introduced to show fur ther results when usingdiflerent alcohols as solvents and when employing the same inhibitingmaterials in concentrations of 0.025% by weight of an unstable gasoline,which is anentirely V practical percentage from the standpoint of cost,clarity of gasoline, color, drop, etc. One part by weight of the samemixture used when obtaining figures in the preceding table was dissolvedin three parts by weight of the alcohol shown.

Eflect of solvents on induction per od In the following specific examplewhich is introduced to show a very practical application of the presenttype of inhibitor to the treatment of an unstable gasoline, a blend ofalcohols was used which apparently has a particularly good solventaction on the isoamyl derivatives mentioned as well as on othercombinations of other compounds. The example is introduced to show thepractical character of the process but is not intended to unduly limitthe scope of the invention.

The blend of alcohols used consisted of 20% by volume of isobutylalcohol with 80% by volume -of absolute methyl alcohol. This blenddissolved an equal part by weight of a mixture which was substantially80% mono iso amyl p-aminophenol and 20% di-iso amyl p-phenylenediamine.solution was perfectly clear and could be added Theto test gasolines inamounts up to 0.1%. without methyl alcohol is considerably cheaper thantheiso butyl alcohol.

The foregoing specification disclosing the character of the inventionwill enable those skilled in the art to which it pertains to approachits commercial value and the data introduced will show the type ofresults obtainable in practice, though neither section is intended to beunduly limiting.

I claim as my invention: 1 l. A method for stabilizing cracked gasolinagainst deterioration which comprises adding to the gasoline analkyl-substituted para-aminophenol and an alkyl-substitutedparaphenylenediamine dissolved in an alcoholic solvent comprising abutyl alcohol.

2; A method for stabilizing cracked gasoline 'against deteriorationwhich comprises adding to the gasoline an alkyl-substitutedpara-aminophenol and an alkyl-substituted paraphenyl- 'enediaminedissolved in an alcoholic solvent comsolved in an alcoholic solventcomprising isobutyl alcohol.

6. An inhibitor for cracked gasoline comprising a mixture of methyl andisobutyl alcohols having dissolved therein an alkyl-substitutedparaaminophenol and an alkyl-substituted para- 1' phenylenediamine.

'7. A method for stabilizing cracked gasoline against deteriorationwhich comprises adding to the gasoline a relatively small amount of asolution of an alkyl-substitutedpara-aminophenol and analkyl-substituted paraphenylenediamine, the first-named compound beingin substantially greater proportion than the second,. and the solvent ofsaid solution comprising a major proportion of methyl alcohol and aminor proportion of an aliphatic alcohol having from 2 to 4 carbonatoms.

8. A method for stabilizing cracked gasoline against deterioration-whichcomprises adding to the gasoline a relatively small amount of a solutionof mono-iso-amyl para-aminophenol and di-iso-amyl paraphenylenediamine,the firstnamed compound being in substantially greater proportion thanthe second, and the solvent of said solution comprising a majorproportion of methyl alcohol and a minor proportion of an,

aliphatic alcohol having from 2 to 4. carbonatoms.

9. A method for stabilizing cracked gasoline the first-named compoundbeing in substantially greater-proportion than the second, andthesolvent of said solution comprising a major pro portion of methylalcohol. and a minor proportion of abutyl alcohol. v

- "10..A method for stabilizing'cracked gasoline against deteriorationwhich comprises adding to the gasoline a relatively small amount of asolution of mono-iso-amyl para-a'minophenol and diiso-amylparaphenylenediamine, the first-named compound being in substantiallygreater propor tion than the second, and the solvent of said solu-.

tion comprising a major proportion of methyl alcohol and a minorproportion of a butyl alcohol.

11. An inhibitor for cracked gasoline comprising a solution of analkyl-substituted para-amino phenol and an alkyl-substitutedparaphenylenediamine, the first-named compound being in substantiallygreater proportion than the second, and the solvent of said solutioncomprising a major proportion of methyl alcohol and a minor proportionof an aliphatic alcohol having from 2 to 4 carbon atoms.

12. An inhibitorfor cracked gasoline comprising a solution ofmono-iso-amyl para-aminophenol and di-iso-amyl paraphenylenediamine.

the first-named compound being in substantially greater proportion thanthe second; and the solvent of said solution comprising a majorproportion of methyl alcohol and a minor proportion of an aliphaticalcohol having from 2 to 4 carbon atoms.

13. Aninhibitor for cracked gasoline compris ing a solution of analkyl-substituted para-aminophenol and an alkyl-substitutedparaphenylenediamine, the ilrst-named compound being in substantiallygreater proportion than the second, i

and the solvent of said solution comprising a major proportion of methylalcohol and a minor proportion of a butyl alcohol.

14. An inhibitor for cracked gasoline compris ing a solution ofmono-iso-amyl para-aminophenol and di-iso-amyl paraphenylenediamine, thefirst-named compound being in substantially greater proportion than thesecond, and the solvent of said solution comprising a major proportionof methyl alcohol and a minor proportion of a butyl alcohol.

, 15. A method for stabilizing cracked gasoline against deteriorationwhich comprises'adding to the gasoline a relatively small amount of asolution of an alkyl-substituted para-aminophenol and analkyl-substituted paraphenylenediamine, the first-named compound beingin substantially greater proportion than the second, and the solvent ofsaid solution comprising a major proportion of a mixture of methylalcohol and an aliphatic alcohol having from 2 to 4 carbon atoms.

1 16. An inhibitor i'orcracked gasoline comprising a solution of analhvl-substituted para-amjor proportion of a mixture of methylalcohol.and an aliphatic alcohol having from 2 to 4 carbon atoms.

CHARLES G. DRYER.

